Absorption refrigeration system of the inert gas type



w. G. KSGEL Aug. 18, 1970 ABSORPTION REFRIGERATION SYSTEM OF THE INERT GAS TYPE Filed Sept. 25. 1968 III.' -II INVENTOR. %M4/i v AT TO R NE Y United States Patent f 3,524,330 ABSORPTION REFRIGERATION SYSTEM OF THE INERT GAS TYPE Wilhelm Georg Kiigel, Stockholm, Sweden, assignor to Aktiebolaget Electrolux, Stockholm, Sweden, a corporation of Sweden Filed Sept. 25, 1968, Ser. No. 762,427 Claims priority, application Sweden, Sept. 29, 1967, 13,436/67 Int. Cl. F25b 15/10 US. Cl. 62-490 Claims ABSTRACT OF THE DISCLOSURE An absorption refrigeration system of the inert gas type in which refrigerant vapor is expelled from solution at a place of heating and condensed at a place of condensation, a circuit for circulating inert gas which includes an absorber and a plurality of cooling elements respectively operable at low and higher temperatures, the circuit having a weak gas line for flowing inert gas weak in refrigerant from the absorber to the low temperature cooling element and a rich gas line for flowing inert gas enriched in refrigerant from the low and higher temperature cooling elements to the absorber, conducting liquid refrigerant from the condenser to the low temperature cooling element in a path of flow which includes a first zone of the rich gas line, conducting inert gas partially enriched in refrigerant from the low temperature element to the first zone of the rich gas line and into the presence of liquid refrigerant therein, the higher temperature cooling element forming apart of the rich gas line at a second zone thereof, and conducting liquid refrigerant from the low temperature cooling element to the higher temperature cooling element in a path of flow which bypasses the first zone of the rich gas line, the higher temperature cooling element being connected in the inert gas circuit to receive inert gas partially enriched in refrigerant in the low temperature cooling element.

BACKGROUND OF INVENTION Field of the invention In absorption refrigeration systems of the inert gas type it has been the practice heretofore to precool liquid refrigerant in its path of flow from a condenser to a cooling unit or the evaporator structure by flowing inert gas enriched in refrigerant into the presence of the liquid refrigerant before the latter is introduced into the cooling unit or evaporator structure which may include a first cooling element operable at a low temperature for freezing purposes and a second cooling element operable at a higher temperature to promote storing of food and the like at a refrigerating temperature above the freezing temperature.

Description of the prior art It has been proposed heretofore to position above an evaporator structure a gas heat exchanger which is connected in the inert gas circuit and through which inert gas rich in refrigerant vapor flows in heat exchange relation with inert gas weak in refrigerant vapor. Inert gas enriched in refrigerant in the evaporator structure flows through the gas heat exchanger into the presence of liquid refrigerant flowing from the condenser to the evaporator structure. Liquid refrigerant in the gas heat exchanger evaporates and takes up heat from liquid refrigerant and also from enriched inert gas. Further, heat exchange is effected between weak and enriched gas in the gas heat exchanger, thereby cooling the weak inert gas. In this way liquid refrigerant and weak inert gas flowing to the evaporator 3,524,330 Patented Aug. 18, 1970 structure are introduced therein at a lower temperature than a temperature when no precooling of these fluids is effected.

Since the gas heat exchanger in its entirety is employed to promote precooling of liquid refrigerant, the function of the gas heat exchanger to effect optimum heat exchange between weak and rich inert gas is impaired. This is so because the weak inert gas flowing to the evaporator structure is not effectively cooled in the gas heat exchanger by its heat interchange with rich inert gas and hence it is introduced into the evaporator structure at a higher temperature than otherwise would result if the gas heat exchanger could function as originally intended.

Moreover, the rich inert gas cooled by evaporation of liquid refrigerant in the gas heat exchanger flows from the latter at a relatively low temperature without being effectively employed to produce refrigeration in the evaporator structure to produce the lowest possible refrigerating temperature, which is objectionable. This is especially true in refrigerators having several thermally segregated compartments in one of which freezing temperatures must be maintained by one evaporator section and satisfactory temperatures must be maintained by another evaporator section to preserve foods and the like at refrigerating temperatures above the freezing temperature.

It also has been proposed to flow weak inert gas from the gas heat exchanger into the presence of liquid refrigerant in a precooler provided in the path of flow of liquid refrigerant from the condenser to the evaporator structure, and, after effecting precooling of liquid refrigerant, flowing the partially enriched inert gas from the precooler to the absorber in the system. However, such a proposal results in loss of useful refrigerating effect. With this arrangement it is necessary to provide two parallel paths of flow for enriched inert gas, one from the precooler to the absorber and the other from the evaporator structure to the absorber. This is objectionable because it is difficult to control flow of inert gas in parallel paths of flow in the inert gas circuit, especially when disturbances can often occur due to changes and variations in conditions encountered during operation of the refrigeration system.

SUMMARY OF THE INVENTION My invention relates to absorption refrigeration systerns of the inert gas type adapted to produce refrigeration at a plurality of temperatures, and it is an object to effect a lower refrigeration temperature in the low temperature part or section of a plural temperature cooling unit or evaporator structure.

In accord with the invention, a substantial cooling output is effected at an extremely low temperature level without jeopardizing the total cooling output of the refrigeration system. I accomplish this by effecting the lower temperature level in such manner that inert gas partially enriched in refrigerant vapor in a low temperature evaporator section of evaporator structure flows therefrom to a first passage of a precooler and into the presence of liquid refrigerant in its path of flow from a condenser to the evaporator structure. The precooler also includes a second passageway through which weak inert gas flows to the low temperature evaporator section. The precooler functions to cool both the liquid refrigerant and Weak inert gas which, after being cooled, together flow to the low temperature evaporator section.

The first passageway of the precooler forms a first zone of a rich gas line for flowing rich inert gas to an absorber from the low temperature evaporator section and a higher temperature evaporator section which is connected in the rich gas line at a second zone thereof. Unevaporated liquid refrigerant flows from the low temperature evaporator section to the higher temperature evaporator sec- 9 tion in a path of flow which bypasses the first zone of the rich gas line. The higher temperature evaporator section is connected in the inert gas circuit to receive inert gas partially enriched in refrigerant in the low temperature evaporator section.

The low and higher temperature evaporator sections respectively are arranged to abstract heat from thermally segregated compartments of an insulated refrigerator cabinet, the low temperature evaporator section functioning to maintain freezing temperatures in one compartment and the higher temperature evaporator section functioning to maintain refrigerating temperatures above the freezing temperature in another compartment.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, the single figure more or less diagrammatically illustrates an absorption refrigeration system of the inert gas type embodying my invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, I have shown my invention in connection with a refrigerator having a thermally insulated space which is divided by a partition 11 into a plurality of compartments 12 and 14 one above the other and arranged to be cooled by a plurality of cooling elements 15 and 16 operable at different temperatures. The cooling elements 15 and 16 are arranged to abstract heat from the interior of the refrigerator 10, the upper compartment 12 being cooled primarily by the cooling element 15 so as to freeze water and other matter as well as store frozen food packages therein.

The partition 11 functions to prevent circulation of air between the upper and lower compartments 12 and 14 and thermally shields the cooling elements 15 and 16 from one another. Hence, the upper and lower compartments 12 and 14 are thermally segregated from one another.

The cooling element 15, which may be in the form of a horizontally disposed looped coil, is provided with a suitable heat dissipating surface, such as the plurality of heat transfer members 15a, for example. The cooling element 16 also may have a suitable heat dissipating surface formed from a plurality of heat dissipating members 16a, for example. The lower compartment 14, which may serve as a space in which food and the like is stored at a temperature above the freezing temperature, is cooled primarily by the cooling element 16.

The cooling elements 15 and 16 constitute the cooling unit or evaporator structure of an absorption refrigeration system of the inert gas type and are connected by conduits to other parts of the system for circulation of inert gas as well as supply liquid refrigerant to the evaporator structure. In a system of this type, refrigerant expelled from a solution in a generator 17 by heating passes upward through an air cooled rectifier 18 into an air cooled condenser 19 in which the expelled refrigerant is condensed and liquefied. Liquid refrigerant flows from condenser 19 through a conduit 20 into a precooler 21 in which precooling of liquid refrigerant is effected, as 'will be described presently, and refrigerant flows therefrom through a conduit 22 into the cooling elements or evaporator sections 15 and 16.

In evaporator sections 15 and 16 the refrigerant evaporates and diffuses into an inert gas, such as hydrogen, for example, to produce a refrigerating effect and abstract heat from the surroundings. The resulting gas mixture of refrigerant and inert gas flows from evaporator sections 15 and 16 through an outer passageway 23 of a gas heat exchanger 24 and a conduit 25 into an absorber comprising a vessel 26 and a looped coil 27. In the absorber vessel 26 and looped coil 27 refrigerant vapor is absorbed into a liquid absorbent, such as water, for example, which enters through a conduit 28. The hydrogen or inert gas, which is practically insoluble and weak in refrigerant, is

returned to evaporator sections 15 and 16 through a conduit 29 and inner passageway 31) of the gas heat exchanger 24.

Absorption liquid enriched in refrigerant in the absorber flows from vessel 26 through a conduit 31 to generator 17 where it is heated and refrigerant vapor again is expelled out of solution. The weakened absorption liquid from which liquid has been expelled flows from generator 17 through a conduit 32 and conduit 28 to coil 27 to absorb refrigerant vapor again, the conduit 32 desirably being in heat exchange relation with conduit 31.

The gas heat exchanger 24 comprises outer and inner conduits 33 and 34 which form the outer and inner passageways 23 and 30, respectively, of the heat exchanger. The conduit 29 for conducting weak inert gas from the upper end of absorber coil 27 to the gas heat exchanger 24 extends downward from the upper end of the coil to a region 35 at the lower end of the gas heat exchanger 24 which is near the absorber vessel 26. The lower end of conduit 29, at the region 35, is connected to the lower end of the conduit 34 which forms the inner passageway 30 of the gas heat exchanger 24. At the region 35 the conduit 34 includes a downward extending portion 34a which extends below the liquid surface level 26a of the body 26b of absorption liquid in the absorber vessel 26. The conduit 25 through which inert gas enriched in refrigerant flows into the absorber vessel 26, on the other hand, discharges the rich gas mixture into the absorber vessel 26 into the vapor space therein above the liquid surface level 26a.

In accordance with my invention, in order to intro duce liquid refrigerant into the cooling element 15 at a lower temperature than the temperature at which it flows from the condenser 19, the refrigerant is cooled in the precooler 21 by flowing liquid refrigerant in the outer passageway 23a thereof in the presence of inert gas partially enriched in refrigerant vapor. The partially enriched inert gas flows from the outlet end of the cooling element or evaporator section 15 through a conduit 36 to the precooler 21 and flows countercurrent to liquid refrigerant in the precooler passageway 23a. Liquid refrigerant in the passageway 23a evaporates and diffuses into the partially enriched inert gas and takes up heat from liquid refrigerant and also from weak inert gas flowing to cooling element or evaporator section 15a through that portion of conduit 34 extending through precooler 21. Stated another way, the precooler 21 functions to lower the temperature of liquid refrigerant in the passageway 23a thereof and also functions to lower the temperature of inert gas weak in refrigerant and flowing through conduit 34 from absorber coil 27. The weak inert gas, after its temperature is reduced, then flows through conduit 22 to the inlet end of the cooling element 15.

After liquid refrigerant flows in heat exchange relation and out of physical contact with weak inert gas in the precooler 21, such cooled liquid refrigerant passes from passageway 23 into the conduit 34 through an opening 37 therein. In this way liquid refrigerant passes through the opening 37 into the presence of weak inert gas flowing through conduit 34 and liquid refrigerant and weak inert gas flow through the conduit 22 to the cooling element 15.

Inert gas partially enriched in refrigerant vapor in the precooler 21 flows therefrom toward the absorber vessel 26 in the outer passageway 23 of gas heat exchanger 24. The outer passageway 23 of the gas heat exchanger is formed by the conduit 33, as explained above, and a portion of this conduit forms the cooling element or evaporator section 16. Unevaporated liquid refrigerant flows from the cooling element 15 through a conduit 38 into the outer passageway 23 of the gas heat exchanger 24 for fiow through the cooling element 16, the conduit 38 being shaped to form a liquid trap.

Since inert gas weak in refrigerant vapor first flows through cooling element 15 and partially enriched inert gas flows successively through the precooler 21 and the cooling element 16, the inert gas in the cooling element contains a lesser amount of refrigerant vapor than the inert gas in the cooling element 16. The partial vapor pressure of the refrigerant is a gradient, so that the temperature in the cooling element 15 and cooling element 16 also is a gradient, the evaporating temperature of liquid refrigerant being lower in cooling element 15 which constitutes the freezing portion of the cooling unit or evaporator structure.

An important aspect of the invention is that inert gas partially enriched in refrigerant vapor in the low temperature cooling element 15 and capable of producing a low temperature refrigerating effect is effectively employed in the precooler 21 to lower the temperature of the weak inert gas and reduce the temperature of the liquid refrigerant flowing to the element 15 and is thereafter employed in the cooling element 16 to produce a sufiiciently low temperature in the compartment 14 in which foods and the like are maintained at a temperature above freezing temperature.

In view of the foregoing, it will now be understood that the conduit 34, which forms the passageway 23 and may be referred to as a weak gas line, extends from the region 35 adjacent to the absorber vessel 26 to the righthand end of the precooler 21. The conduit 33, which envelops the conduit 34 to provide the passageway 23 and may be referred to as a rich gas line, extends from the cooling elements 15 and 16 to the absorber vessel 26. The precooler 21 may be formed by the upper end of conduit 34 and the passageway 23a thereof constitutes a first zone of the rich gas line, such first zone 23a forming a part of the conduit means for flowing liquid refrigerant from the condenser 19 to the first cooling element 15.

Inert gas partially enriched in refrigerant in the first cooling element 15 flows from the outlet end thereof through conduit 36 to the first zone 23a of the rich gas line into the presence of liquid refrigerant flowing thereto from the condenser or refrigerant liquefying means 19. The second cooling element 16 forms a part of the rich gas line or passageway 23 at a second zone of the line. Unevaporated liquid refrigerant flows from the first cooling element 15 through conduit 38 into the rich gas line or passageway 23 for flow to the second cooling element 16. Hence, liquid refrigerant flows from the first cooling element 15 to the second cooling element 16 in a path of flow which bypasses the first zone or passageway 23a in the rich gas line. As explained above, the second cooling element 16 is connected in the inert gas circuit to receive inert gas partially enriched in the first cooling element 15. More specifically, the second element 15 is connected in the rich gas line of the inert gas circuit to receive from the first zone or passageway 23a thereof inert gas partially enriched in refrigerant.

As shown in the drawing, the first and second gas heat exchanger passageways and 23 respectively form the weak and rich gas lines and the passageway 23a of the precooler 21 forms the first zone or part 23a of the rich gas line. More specifically, the first zone or passageway 23a of the precooler 21 and the second zone or part of passageway 23 employed as the second cooling element 16 both form parts of the rich gas line of the inert gas circuit.

Liquid refrigerant flows in the first zone or passageway 23a of the rich gas line in the presence of partially enriched inert gas, such flow taking place in heat exchange relation and out of physical contact with inert gas in the weak gas line. Thereafter, the liquid refrigerant passes through the opening 37 at the right-hand end of conduit 34 in precooler 21 in the presence of weak inert gas and flows with the latter to the cooling element 15. The opening 37 is normally closed by liquid refrigerant passing therethrough, thus blocking flow of inert gas between the outer and inner passageways of the precooler 21. If desired, a screen (not shown) may be provided at the opening 37 to promote sealing thereof by liquid refrigerant.

The precooler 21 is inclined to the horizontal so that a body of liquid refrigerant will collect at the right-hand end of the precooler at the vicinity of the opening 37 to close the opening and promote gravity How of liquid therethrough from the condenser 19 to the cooling element 15.

I claim:

1. In a refrigerator,

(a) a cabinet comprising thermally insulated walls defining an insulated interior having a plurality of spaces thermally segregated from one another, one of said spaces functioning as a freezing compartment and the other of said spaces functioning as a compartment for storing foods at a temperature above freezing temperature,

(b) an absorption refrigeration system of the inert gas type comprising a vapor expulsion unit for expelling refrigerant vapor from solution,

(0) refrigerant liquefying means in which liquefaction of expelled vapor is effected,

(d) a gas circuit including an absorber having an inlet for inert gas enriched in refrigerant vapor and an outlet for inert gas weak in refrigerant vapor and a plurality of cooling elements each respectively having an inlet and outlet for inert gas,

(e) said cooling elements including a first cooling element arranged to abstract heat from the freezing compartment and a second cooling element arranged to extract heat from the food storage compartment,

(f) said gas circuit including a weak gas line for flowing inert gas weak in refrigerant vapor from the outlet of said absorber to the inlet of said first cooling element and a rich gas line for flowing inert gas enriched in refrigerant vapor from said first and second cooling elements to the inlet of said absorber,

(g) first conduit means including a first zone of said rich gas line for flowing liquid refrigerant from said refrigerant liquefying means to said first cooling element,

(h) means for conducting inert gas partiall enriched in refrigerant vapor from the outlet of said first cooling element to said first zone of said rich gas line into the presence of liquid refrigerant flowing thereto from said refrigerant liquefying means,

(i) said second cooling element forming a part of said rich gas line at a second zone thereof,

(j) second conduit means for conducting liquid refrigerant from said first cooling element to said second cooling element in a path of flow which bypasses said first zone in said rich gas line, and

(k) said second cooling element being connected in said inert gas circuit to receive inert gas partially enriched in refrigerant in said first cooling element.

2. Apparatus as set forth in claim 1 in which said second cooling element is connected in said rich gas line of said inert gas circuit to receive from said first zone thereof inert gas partially enriched in refrigerant vapor.

3. Apparatus as set forth in claim 2 which includes a gas heat exchanger having first and second passageways, said first passageway forming a part of said weak gas line and said second passageway forming a part of said rich gas line including said second zone thereof.

4. Apparatus as set forth in claim 2 which includes a gas heat exchanger having a first inner passageway and a second outer passageway enveloping said first inner passageway, said first inner passageway forming a part of said weak gas line and said second outer passageway forming a part of said rich gas line including both said first and second zones thereof.

5. Apparatus as set forth in claim 4 in which said gas heat exchanger includes provisions whereby, after liquid refrigerant flows in said first zone of said rich gas line in heat exchange relation with said weak gas line and out of physical contact with inert gas in said weak gas line, the liquid refrigerant then flows into said weak gas line for flow therein in the presence of weak inert gas.

6. Apparatus as set forth in claim in which said gas heat exchanger comprises inner and outer conduits respectively forming said first inner and second outer passageways, and said inner conduit being apertured at said first zone of said rich gas line for liquid refrigerant to flow from said rich gas line into said weak gas line and block flow of gas between said lines.

7. Apparatus as set forth in claim 5 in which liquid refrigerant and said inert gas partially enriched in refrigerant flow countercurrent to one another in said first zone of said rich gas line.

8. Apparatus as set forth in claim 5 in which the rich and weak inert gas lines at the first zone of said rich gas line are inclined to the horizontal for liquid refrigerant to flow by gravity from said refrigerant liquefying means to the inlet of said first cooling element.

9. An absorption refrigeration system of the inert gas type comprising (a) a vapor expulsion unit for expelling refrigerant vapor from solution,

(b) refrigerant liquefying means in which liquefaction of expelled vapor is effected,

(c) a gas circuit including an absorber having an inlet for inert gas enriched in refrigerant vapor and an outlet for inert gas weak in refrigerant vapor and a plurality of cooling elements each respectively having an inlet and outlet for inert gas,

(d) said cooling elements including a first cooling element operable at one temperature and a second cooling element operable at a higher temperature,

(e) said gas circuit including a weak gas line for flowing inert gas weak in refrigerant vapor from the outlet of said absorber to the inlet of said first cooling element and a rich gas line for flowing inert gas enriched in refrigerant vapor from said first and second cooling elements to the inlet of said absorber,

(f) first conduit means including a first zone of said rich gas line for flowing liquid refrigerant from said refrigerant liquefying means to said first cooling element,

(g) means for conducting inert gas partially enriched in refrigerant vapor from the outlet of said first coolling element to said first zone of said rich gas line into the presence of liquid refrigerant flowing thereto from said refrigerant liquefying means,

(h) said second cooling element forming a part of said rich gas line at a second zone thereof,

(i) second conduit means for conducting liquid refrigerant from said first cooling element to said second cooling element in a path of flow which bypasses said first zone in said rich gas line, and

(i) said second cooling element being connected in said inert gas circuit to receive inert gas partially enriched in refrigerant in said first cooling element.

10. Apparatus as set forth in claim 9 in which said second cooling element is connected in said rich gas line of said inert gas circuit to receive from said first zone thereof inert gas partially enriched in refrigerant vapor.

LLOYD L. KING, Primary Examiner US. Cl. X.R. 62492 

